fix upgrade redirect

Author: norareidy

4.0/upgrading/index.html

@@ -17,9 +17,9 @@
 <link rel="stylesheet" href="/mongo-java-driver/5.0/css/java.css" type="text/css" />
 
 
-  <link rel="canonical" href="https://www.mongodb.com/docs/drivers/java/sync/current/"/>
+  <link rel="canonical" href="https://www.mongodb.com/docs/drivers/java/sync/current/reference/upgrade/"/>
   <meta http-equiv="content-type" content="text/html; charset=utf-8" />
-  <meta http-equiv="refresh" content="0;url=https://www.mongodb.com/docs/drivers/java/sync/current/" />
+  <meta http-equiv="refresh" content="0;url=https://www.mongodb.com/docs/drivers/java/sync/current/reference/upgrade/" />